Exception handling consolidation in command handlers.

Use Context.Output to write error messages when you handle an Exception or an error case. If you can't recover afterwards, just return.
Don't throw an exception from within the handler unless necessary.
-> If you want to throw due to an inner exception, throw an OrchardException. Add an error message and the exception as the innerexception of your OrchardException.
Your exception will be caught by the command executive, an error message will indicate which command failed, and the inner exceptions will be displayed.
Also, do not return values from commands, they are not services.

--HG--
branch : 1.x
extra : transplant_source : %5Ej%123%DA%E0%28%A7l%F5%F9%A4%B0z%05%EB%E4%21%FD%DC

src/Orchard.Web/Modules/Orchard.CodeGeneration/Commands/CodeGenerationCommands.cs

@@ -54,12 +54,12 @@ namespace Orchard.CodeGeneration.Commands {
         [CommandName("codegen datamigration")]
         public void CreateDataMigration(string featureName) {
             Context.Output.WriteLine(T("Creating Data Migration for {0}", featureName));
-
             ExtensionDescriptor extensionDescriptor = _extensionManager.AvailableExtensions().FirstOrDefault(extension => DefaultExtensionTypes.IsModule(extension.ExtensionType) &&
                                                                                                              extension.Features.Any(feature => String.Equals(feature.Id, featureName, StringComparison.OrdinalIgnoreCase)));
 
             if (extensionDescriptor == null) {
-                throw new OrchardException(T("Creating data migration failed: target Feature {0} could not be found.", featureName));
+                Context.Output.WriteLine(T("Creating data migration failed: target Feature {0} could not be found.", featureName));
+                return;
             }
 
             string dataMigrationFolderPath = HostingEnvironment.MapPath("~/Modules/" + extensionDescriptor.Id + "/");
@@ -72,7 +72,8 @@ namespace Orchard.CodeGeneration.Commands {
             }
 
             if (File.Exists(dataMigrationFilePath)) {
-                throw new OrchardException(T("Data migration already exists in target Module {0}.", extensionDescriptor.Id));
+                Context.Output.WriteLine(T("Data migration already exists in target Module {0}.", extensionDescriptor.Id));
+                return;
             }
 
             List<SchemaCommand> commands = _schemaCommandGenerator.GetCreateFeatureCommands(featureName, false).ToList();
@@ -115,7 +116,8 @@ namespace Orchard.CodeGeneration.Commands {
             Context.Output.WriteLine(T("Creating Module {0}", moduleName));
 
             if ( _extensionManager.AvailableExtensions().Any(extension => String.Equals(moduleName, extension.Name, StringComparison.OrdinalIgnoreCase)) ) {
-                throw new OrchardException(T("Creating Module {0} failed: a module of the same name already exists", moduleName));
+                Context.Output.WriteLine(T("Creating Module {0} failed: a module of the same name already exists", moduleName));
+                return;
             }
 
             IntegrateModule(moduleName);
@@ -128,14 +130,16 @@ namespace Orchard.CodeGeneration.Commands {
         public void CreateTheme(string themeName) {
             Context.Output.WriteLine(T("Creating Theme {0}", themeName));
             if (_extensionManager.AvailableExtensions().Any(extension => String.Equals(themeName, extension.Id, StringComparison.OrdinalIgnoreCase))) {
-                throw new OrchardException(T("Creating Theme {0} failed: an extention of the same name already exists", themeName));
+                Context.Output.WriteLine(T("Creating Theme {0} failed: an extention of the same name already exists", themeName));
+                return;
             }
 
             if (!string.IsNullOrEmpty(BasedOn)) {
                 if (!_extensionManager.AvailableExtensions().Any(extension =>
                     string.Equals(extension.ExtensionType, DefaultExtensionTypes.Theme, StringComparison.OrdinalIgnoreCase) &&
                     string.Equals(BasedOn, extension.Id, StringComparison.OrdinalIgnoreCase))) {
-                    throw new OrchardException(T("Creating Theme {0} failed: base theme named {1} was not found.", themeName, BasedOn));
+                    Context.Output.WriteLine(T("Creating Theme {0} failed: base theme named {1} was not found.", themeName, BasedOn));
+                    return;
                 }
             }
             IntegrateTheme(themeName, BasedOn);
@@ -151,7 +155,8 @@ namespace Orchard.CodeGeneration.Commands {
                                                                                                              string.Equals(moduleName, extension.Name, StringComparison.OrdinalIgnoreCase));
 
             if (extensionDescriptor == null) {
-                throw new OrchardException(T("Creating Controller {0} failed: target Module {1} could not be found.", controllerName, moduleName));
+                Context.Output.WriteLine(T("Creating Controller {0} failed: target Module {1} could not be found.", controllerName, moduleName));
+                return;
             }
 
             string moduleControllersPath = HostingEnvironment.MapPath("~/Modules/" + extensionDescriptor.Id + "/Controllers/");
@@ -163,7 +168,8 @@ namespace Orchard.CodeGeneration.Commands {
                 Directory.CreateDirectory(moduleControllersPath);
             }
             if (File.Exists(controllerPath)) {
-                throw new OrchardException(T("Controller {0} already exists in target Module {1}.", controllerName, moduleName));
+                Context.Output.WriteLine(T("Controller {0} already exists in target Module {1}.", controllerName, moduleName));
+                return;
             }
 
             string controllerText = File.ReadAllText(templatesPath + "Controller.txt");